Efforts to control termites within the United States cost in excess of one billion dollars per year. Termites, insects of the order Isoptera, feed mainly on cellulose-based materials, and if unchecked, can do appreciable damage to wooden buildings, certain crops, paper and other articles which contain cellulose.
Termite activity can be detected using systems where a food material, typically a cellulose containing material, is placed at a location where termite activity is suspected or likely to occur and the material periodically monitored to determine if termites are feeding on the material. In some recent efforts to monitor and control termites, once feeding activity on the cellulose containing material used at the monitoring site is observed, a slow acting toxicant is added to the material such that the termites that feed on the baited material carry the toxicant back to the termite colony thereby helping to reduce or eliminate the termite colony. Slow acting toxicants are employed so that the termites live long enough to return to the termite colony and deliver toxicant to other members of the colony via trophallaxis. In addition, trail pheromones left by the foraging termites may result in additional termites feeding on the baited material which in turn leads to additional quantities of the toxicant being carried back to the termite colony. In at least one commercial treatment scheme, when termite workers are found attacking the food material at the monitoring site, the termites are collected and placed in a bait tube wherein the termites must eat their way through a food material containing a toxicant in order to return to the termite colony. This procedure helps to ensure that termites returning to the colony induce or "recruit" other termites to feed at the bait tube.
The ideal toxicant for use in schemes to control termites using returning colony members to deliver toxicant to the colony would act slowly enough so that a significant amount of toxicant is returned to the colony, but fast enough so that the colony is eliminated quickly.
Benzoylphenylureas are known class of insecticidal compounds. Their mode of action is inhibition of chitin synthesis. Juvenile hormone mimics are another known class of insecticides. Use of 1[3,5-dicloro-4-(1,1,2,2-tetrafluoroethoxy)phenyl]-3-(2,6-difluorobenzoyl) urea (hexaflumuron) as a termiticide is disclosed in U.S. Pat. No. 5,556,883. Use of (RS)-1-[2,5-dichioro-4-(1,1,2,3,3,3-hexafluoropropoxy)phenyl]-3-(2,6-diflu orobenzoyl)urea (lufenuron) as a termiticide is disclosed in WO 95/16354. Use of 1-(4-chloropnonyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) as a termiticide is disclosed in A. A. Faragalla et al. "Field Evaluation of the Effects of the Juvenile Hormone Analogues (JHA's) and Diflubenzuron (Dimilin) on Termites of the Genus Microcerotermes (Isoptera: Termitidae) in the Central Region of Saudi Arabia," Sociobiology 1985, 11, 29-37.
The combination of a juvenile hormone mimic with a benzoylphenylurea has previously been tested against some insects other than termites, but with mixed results. Simultaneous application of the juvenile hormone analogue methoprene with 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) or (N-[trifluoromethoxy)phenyl]carbamoyl-2-chlorobenzamide in a ratio of 1:9 methoprene:benzoylphenylurea (BAY SIR 8514) was reported to give no advantage in treatment of spruce budworm, but simultaneous application of methoprene and) (N-[[[5-(4-bromophenyl)-6-methyl-2-pyrazinyl]amino]carbonyl]-2-chlorobenza mide (EL-127063) was reported to give a significant advantage. J. L. Robertson et al., "Joint Action of a Juvenile Hormone Analogue with Benzoyiphenylureas ingested by Western Spruce Budworm, Choristoneura occidentalis (Lepidoptera: Tortiricidae)" Can. Ent. 1984, 116, 1063-68.
The results of testing mixtures of diflubenzuorn/methoprene and diflubenzuorn/triprene on eggs of various ages of cotton leafworm Spodoptora littoralis Boisd. are reported in M. A. El-Guindy et al., "The Ovicidal Action of Insecticides and Insect Growth Regulator/Insecticide Mixtures on the Eggs of Various Ages of Susceptible and Diflubenzuron-resistant Strains of Spodoptera littoralls Boisd." Pestic. Sci. 1983, 14, 253-260. A strain susceptible to diflubenzuron and a strain resistant to diflubenzuron were tested. Diflubenzuorn/triprene showed an additive effect on 0-1 day old eggs of the S strain. Diflubenzuron/methoprene was reported to show moderate synergism on 0-1 day old eggs of the susceptible strain; however, the synergistic effect was replaced by an antagonistic effect for eggs 1-2 days old and eggs 2-3 days old. The diflubenzuorn/methoprene combination also showed antagonism when tested on the resistant strain.